Differential for Motorcycle Trike

ABSTRACT

A tilting suspension system is adapted for use with a vehicle having three wheels and a frame. The system has two sets of control arms, each set of control arms being pivotally connected to one side of the frame. An upright is pivotally connected to each set of control arms, each upright having a rotatable hub for allowing one of the wheels to be mounted thereto. Two rocker arms are pivotally connected to the frame, and a control link is pivotally connected to each of the rocker arms, such that pivoting of one rocker arm causes corresponding pivoting of the other rocker arm. A link member operably connects each rocker arm to a corresponding upright, such that pivoting of each rocker arm causes corresponding movement of the uprights. An actuator is configured to selectively pivot the rocker arms, such that actuation of the actuator pivots the rocker arms, thereby causing the frame to rotate about a generally longitudinal roll center and causing each upright to rotate about a generally longitudinal axis.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.12/033,999, filed on 20 Feb. 2008, titled “Tilting IndependentSuspension System for Motorcycle Trike,” which was a continuation ofU.S. application Ser. No. 11/007,851, filed on 9 Dec. 2004, titled“Tilting Independent Suspension System for Motorcycle Trike,” whichclaimed the benefit of U.S. Provisional Application No. 60/528,041,filed 9 Dec., 2003, titled “Tilting Independent Suspension System forMotorcycle Trike,” and which claimed the benefit of U.S. ProvisionalApplication No. 60/539,457, filed 27 Jan. 2004, titled “TiltingIndependent Suspension System for Motorcycle Trike,” and which claimedthe benefit of U.S. Provisional Application No. 60/558,006, filed 31Mar. 2004, titled “Tilting Independent Suspension System for MotorcycleTrike,” all of which are hereby incorporated by reference for allpurposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to motorcycle trikes. In particular, thepresent invention relates to suspension systems for motorcycle trikes.

2. Description of Related Art

Motorcycles are turned by both turning the handlebars and leaning intothe turn. At high speeds, motorcycles can be turned simply by leaninginto the turn. The ability to lean into the turn makes the motorcycleeasier to handle in the turns.

However, when motorcycles are converted into three-wheeled trikes, thisability to lean into the turn is lost. This makes it difficult to handlethe trike when turning, particularly at high speeds.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed to be characteristic of the invention areset forth in the appended claims. However, the invention itself, as wellas a preferred mode of use and further objectives and advantagesthereof, will best be understood by reference to the following detaileddescription when read in conjunction with the accompanying drawings,wherein:

FIG. 1 is a perspective view of a motorcycle trike having a tiltingindependent suspension system according to the present invention;

FIG. 2 is a schematic of the suspension system according to the presentinvention, the suspension system being shown in a non-tilting mode;

FIG. 3 is a schematic of the suspension system of FIG. 2 shown in atilting mode;

FIG. 4 is a schematic of an alternative embodiment of a tiltingindependent suspension system for a motorcycle trike according to thepresent invention;

FIG. 5 is a perspective view of a motorcycle trike having a tiltingindependent suspension system according to the present invention inwhich the trike has two front wheels and one rear wheel;

FIG. 6 is a perspective view of a differential according to the presentinvention for the tilting independent suspension system of theinvention;

FIG. 7 is another perspective view of the differential of FIG. 6 showingan alternate reduced size cover plate;

FIG. 8 is a perspective view of the differential of FIG. 6 shown withthe cover plate removed;

FIG. 9 is a perspective view of the differential of FIG. 6 shown withthe cover plate and one of the bevel gears removed;

FIG. 10 is a perspective view of the differential of FIG. 6 showninstalled on a motorcycle having a shaft-drive transmission;

FIGS. 11A-14F are various views of several different adapter bracketsused with the present invention; and

FIG. 15 is a perspective view of a rolling chassis for a motorcycletrike and according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1 in the drawings, a motorcycle trike, or trike 11,having a tilting independent suspension system according to the presentinvention is illustrated. Trike 11 is three-wheeled motorcycle having asingle front wheel 13, and two rear wheels 15 and 17. A frame 19 carriesan engine 21 and a transmission 23. Front wheel 13 is coupled to frame19 via a front fork and suspension system 25. Rear wheels 15 and 17 arecoupled to frame 19 via a tilting independent suspension system 27.

Referring now to FIGS. 2 and 3 in the drawings, tilting independentsuspension system 27 is illustrated. Suspension system 27 is preferablya double control-arm suspension and is operable between a non-tiltingmode, as is shown in FIG. 2, and a tilting mode, as is shown in FIG. 3.Trike 11 operates in the non-tilting mode when traveling in a straightdirection, but transitions into the tilting mode when turning. Thisprovides for better, safer, and more enjoyable handling of trike 11.

Transmission 23 includes a belt drive or drive shaft unit 30, adifferential 31, at least one disk brake 32, axles 33, universal joints35, half shaft drive links 37, wheel uprights 39, and wheel hubs 41.Wheels 15 and 17 are fastened to wheel hubs 41. Uprights 39 areconnected to frame 19 via upper and lower controls arms, shown in thefigures as upper H-arms 43 and lower H-arms 45, which cooperate to alloweach upright 39 to move in a generally vertical path relative to frame19 as H-arms 43, 45 pivot relative to frame 19. Frame 19 includes towers46 that extend generally upward from each side of frame 19. The movementof each upright 39 is constrained and damped by a shock absorber 47,which may be an air shock absorber or any other appropriate type ofsuspension damper.

The unique tilting feature of the subject invention is facilitated bytwo opposing rotating rocker arms 51. In the preferred embodiment, eachrotating rocker arm 51 is V-shaped, having an interior leg 52 and anexterior leg 54, such that interior legs 52 and exterior legs 54 meet atvertices 56 and rotate relative to frame 19 about pivot pins 58. It willbe appreciated that rotating rocker arms 51 may be of different shapes,sizes, and configurations. Rotating rocker arms 51 are pivotallyconnected to towers 46 at vertices 56. The upper ends of shock absorbers47 are pivotally coupled to exterior legs 54, and the lower ends ofshock absorbers 47 are pivotally coupled to lower H-arms 45. Shockabsorbers 47 and lower H-arms 45 form tilt angles A. The two rotatingrocker arms 51 are rigidly and pivotally linked together by anadjustable connecting rod 53 that extends between interior legs 52.

Connecting rod 53 is selectively driven in opposing directions by acontrol actuator 55. Control actuator 55 may be a pneumatic, hydraulic,electric, or magnetic device, and actuator 55 is controlled by a controlsystem 57. Actuator 55 may be a ball-screw device or other similarelectro-mechanical device. Control system 57 is activated by one or moresensors 59 operably associated suspension system 27. Sensors 59preferably sense the orientation, speed, and/or acceleration of trike11, and may be pneumatic, hydraulic, electric, or magnetic devices, orany other suitable sensing apparatus.

In the preferred embodiment, suspension system 27 allows free movementof uprights 39 until a selected tilt angle A is reached. When theselected tilt angle A is reached, such as during a turn, control system57 is activated by sensor 59. Control system 57 then actuates actuator55, thereby causing movement of connecting rod 53 and correspondingrotational movement of rotating rocker arms 51 about pivot pins 58. Therotational movement of rotating rocker arms 51 causes frame 19 to tiltin the direction of the turn, thereby improving the handling of trike11. It will be appreciated that a full lean is not necessary. Onepurpose of suspension system 27 is to “break” the steering so that frontfork and suspension system 25 “falls” into the turn more easily.

Referring now to FIG. 4 in the drawings, an alternate embodiment oftrike 11 is illustrated. In this embodiment, control actuator 55 isdisposed between one of towers 46 and one of rocker arms 51. In thisembodiment, it is preferred that one end of control actuator 55 bepivotally mounted to tower 46 at a pivot pin 58, and the other end ofcontrol actuator 55 be pivotally mounted to rocker arm 51 at a secondpivot pin 60. As shown in the FIG. 4, control actuator 55 includes ahousing 69 that defines two opposing fluid chambers 71 and 73 that areseparated by a piston 75. Piston 75 is connected to an elongated shaft77. Housing 69 is pivotally connected to pivot pin 58, and elongatedshaft 77 is pivotally connected to pivot pin 60. Fluid chambers 71 and73 are in fluid communication with a control box 79 via conduits 81 and83. Though shown in the figure as a pneumatic or hydraulic type,actuator 55 may be of any appropriate type, as described above.

Control box 79 includes vent ports 85 and 87 that are operablyassociated with fluid chambers 71 and 73, respectively. It will beappreciated that in applications in which the control fluid is air, ventports 85 and 87 may be open to the environment; and that in applicationsin which the control fluid is a hydraulic fluid, vent ports 85 and 87would be in fluid communication with a fluid reservoir. Control box 79is in fluid communication with a source of pressurized fluid, such aspressurized tank 89, via a conduit 91. Pressurized tank 89 suppliespressurized fluid to control box 79 for controlling control actuator 55.It is preferred that the fluid in control system 57 be air, and thattank 89 be maintained at about 80 psi. However, it should be understoodthat a wide variety of control fluids may be used over a wide range ofpressures, depending upon the desired application, responsiveness, andcost.

Tank 89 is in fluid communication with and pressurized by a compressor93. A one-way check valve 95 and a pressure switch 97 may be disposedbetween compressor 95 and tank 89. One-way check valve 95 ensures thatthe fluid does not pass back through to compressor when compressor is inthe off mode. Pressure switch 97 turns off compressor 95 when tank 89has reached the desired pressure, and prevents compressor 95 fromover-pressurizing control system 57.

In operation, when trike 11 is traveling straight, control actuator 55is in a trim condition in which the pressures in chambers 71 and 73 areequalized. When trike 11 goes into a turn, sensors 59 send a signal tocontrol box 79. Control box 79 then selectively increases the pressurein one of chambers 73 or 75, and correspondingly decreases the pressurein the other chamber. Vent ports 85 and 87 allow the fluid from thedepressurized chamber to be appropriately vented. As a result, piston 75moves in one direction or the other. Because housing 69 is pivotallymounted to tower 46, movement of piston 75 causes a correspondingrotation of rocker arms 51. The rotational movement of rotating rockerarms 51 causes frame 19 to tilt in the direction of the turn, therebyimproving the handling of trike 11. Control system 57 will maintaintrike 11 in the tilted mode as long as sensors 59 sense that trike 11 isin the turn. As trike 11 leaves the turn and returns to straight travel,control box 79 causes the pressure in chambers 71 and 73 to againequalize and return control actuator 55 to the trim condition.

It will be appreciated that control system 57 is preferably programmedor adjusted to provide a safe and smooth transition between tilting andstraightening out. It should be understood that control system 57 may beoperated manually or may be automated by computers, microprocessors, orany of a wide variety of automated control devices. For example, sensors59 may be manual switches (not shown) disposed on the handlebars oftrike 11 that are operated by the rider, or control system 57 may beconfigured to operate automatically without any input from the rider. Inaddition, it will be appreciated that trike 11 may include a means formanual or automatic override of control system 57.

Referring now to FIG. 5 in the drawings, an alternate embodiment of thepresent invention is illustrated. In this embodiment, a trike 111 hastwo front wheels 113, 115 and one rear wheel 117. In this embodiment, asuspension system 127, which is similar in form and function tosuspension system 27, is operably associated with the front wheelsinstead of the rear wheels. Suspension system 127 allows front wheels113, 115 to tilt when trike 111 turns, making trike 111 easier tohandle.

As is shown, trike 111 may include a body portion 119 that covers orencloses all or part of suspension system 127. In those embodiments inwhich body portion 119 includes a main body 121 and separate fenders123, 125, it will be understood that suspension system 127 may beappropriately scaled down in size and shape, or relocated on trike 111to fit within the confines of main body 121 and/or fenders 123, 125. Forexample, the rotating rocker arms, the adjustable connecting rod, thecontrol actuator, and the other components of suspension system 127 maybe located beneath or in the same plane as the differential. One benefitof the present invention is that the components can be located in a widevariety of locations on the trike without adversely affecting theoperation of the suspension system.

Referring now to FIGS. 6-10 in the drawings, differential 31 is shown invarious views. In FIG. 6, differential 31 is shown installed insuspension system 27. Differential 31 is fixed to and rotates with adrive pulley 154 for transmitting torque to the wheels of the trike.Differential 31 includes a base portion 151 and a cap portion 153 thatencloses differential 31. Base portion 151 includes two inserts 155, 157that allow access to the interior of differential 31 for assembly andmaintenance, and that provide internal operating surfaces for a pair ofopposing bevel gears 159, 163. Cap portion 153 also functions as aspacing means that allows differential 31 to be used to convert bothshaft-drive and belt-drive motorcycles to trikes. In FIGS. 6 and 7,differential 31 is shown installed on a belt-drive trike. In FIG. 10,cap portion 153 of differential 31 has been replaced with an alternate,reduced size cap portion 156. Cap portion 156 allows differential 31 tobe used installed on a shaft-drive trike. Cap portions 153 and 156 areshown side-by-side in FIG. 7 for comparative purposes.

Differential 31 includes a plurality of internal bevel gears 159, 161,163, 165 that allow the two wheels of the trike, whether located on thefront or on the rear, to rotate at different speeds as the trike travelsthrough turns. Gears 159 and 163 oppose each other and rotate on concavesupport surfaces located on the interior surfaces of inserts 155, 157.Gears 159 and 163 are supported by a fixed shaft 169. Gears 161 and 165oppose each other and are coupled together via gears 159 and 163. Gears161 and 165 include internal splines 172 that are configured to matinglyreceive splined drive shafts (not shown) that extend outward from eachside of differential 31 to continuously variable universal joints 171,173. Gears 159, 161, 163, 165 rotate with base portion 151 and capportion 153 and do no rotate relative to each other unless the trike isturning.

In FIG. 10, differential 31 is installed on a trike 189 having ashaft-drive transmission. Torque is transmitted to differential 31 froma drive shaft 191 through a 90° coupling member 193. Thinner cap portion156 is best suited for this embodiment, due to the thickness of couplingmember 193. In this embodiment, the splined shaft on the side ofcoupling member 193 is longer so that it can pass through couplingmember 193 to the continuously variable universal joint on that side. Inthese shaft-drive embodiments, the suspension system is mounted to themotorcycle with an adapter bracket 195, a mounting link 197, and asecond hatchet-shaped adapter bracket (see FIGS. 11A-11G).

Referring now to FIGS. 11A-14G in the drawings, several differentadapter brackets that are used to mount the suspension system to themotorcycle frame are illustrated. The adapter brackets shown in FIGS.11A-12G are typically used to convert shaft-drive motorcycles to trikes.In FIGS. 11A-11G, an adapter bracket 201 for converting a shaft-drivemotorcycle to a trike is shown. Adapter bracket 201 includes a couplingend 203 and a shaft end 205 that is configured to be coupled to and/ortelescopically mate with the frame of the motorcycle. Adapter bracket195 is shown in FIGS. 12A-12G.

The adapter brackets shown in FIGS. 13A-14F are typically used toconvert belt-drive motorcycles to trikes. Adapter bracket 301 shown inFIGS. 13A-13 includes one or more arcuate slots 303 that allow thesuspension system to rotate about a pivot point 305. This allows thebelt to be placed over the belt drive pulley and adjusted. Likewise,adapter bracket 401 shown in FIGS. 14A-14F includes one or more arcuateslots 403 that allow the suspension system to rotate about a pivot point405. The dashed lines indicate that the shape of that portion of bracket401 may vary.

In another embodiment of the present invention, the belt drive pulleyincludes a central, hollowed-out can-shaped portion. This can shapedportion allows the differential and bearings to be completely orpartially recessed therein. This configuration allows longer driveshafts to be used, which in turn, allows the suspension system to have agreater range of tilting angles.

The suspension system of the present invention is particularly wellsuited for use in a universal rolling chassis according to the presentinvention. Such a universal rolling chassis allows a user to installengines from a wide variety of manufacturers with little or nomodification to the rolling chassis or suspension system. FIG. 15 showsa rolling chassis 501 having a frame 503, front suspension 505, and reartilting suspension 507. A front wheel 509 is attached to frontsuspension 505, and rear wheels 511, 513 are attached to rear suspension507. Frame rails 515, 517 support an engine installed within frame 503.

It is apparent that an invention with significant advantages has beendescribed and illustrated. Although the present invention is shown in alimited number of forms, it is not limited to just these forms, but isamenable to various changes and modifications without departing from thespirit thereof. For example, the invention is described as being used inmotorcycles, but it should be understood that the tilting suspensionsystem may also be used for other types of vehicles.

1. A differential, comprising: a housing; a first insert releasablycoupled to the housing, the first insert having a concave internalsurface; a pair of opposing pinion gears disposed within the housing, atleast one of the pinion gears having an external convex surfaceconfigured to mate with the internal concave surface of the firstinsert; and a pair of opposing bevel gears disposed within the housingand matingly coupled to the pair of opposing pinion gears, each bevelgear having internal splines for transmitting torque to a correspondingdrive axle.
 2. The differential according to claim 1, furthercomprising: a second insert releasably coupled to the housing, thesecond insert being located opposite the first insert and having aconcave internal surface configured to mate with a convex externalsurface of the other pinion gear.
 3. The differential according to claim1, further comprising: a cap member for enclosing the housing, the capmember being configured such that the cap member may be interchangedwith cap members of different sizes, whereby the housing may be utilizedwith both belt-drive transmissions and direct-drive transmissions. 4.The differential according to claim 1, wherein the pinion gears areinterchangeable with pinion gears of different sizes and the bevel gearsare interchangeable with bevel gears of different sizes.